Parametric study of two degree-of-freedom vortex-induced vibrations of a cylinder in a two-dimensional flow

We derive accurate, continuous response surfaces of two degree-offreedom vortex- induced vibrations (VIV) of flexibly mounted cylinders, for a wide range of transverse and in-line natural frequencies, to identify the parametric sensitivity of the VIV response. The flow is assumed to be two-dimensional and the Reynolds number equal to 1,000; the structure has the same low damping for the inline and transverse motions, while the transverse and in-line mass ratios are equal. The VIV response is studied within a wide range of the transverse natural frequency around the synchronization region. The variation of the in-line natural frequency is chosen to be larger than for the transverse natural frequency, in order to study multimodal response. The numerical technique uses a stochastic generalized Polynomial Chaos representation coupled to a spectral element based deterministic solver; hence the response is obtained as a continuous function of the parameters.